1. Field of the Invention
The present invention is related to optical projection systems, and more particularly, to optical projection systems used during the assembly or inspection of objects.
2. Description of Related Art
During the manufacturing of an object, measurements are typically taken of various parameters of the object and features or details of that object are often located for verification purposes. Depending upon the size and shape of the object, the measurements may be relatively difficult to make. In particular, physical measurements, such as thickness or length, often depend upon the exact locations of the object from which the measurements are taken, most notably with traditional vision systems for measurements. For manual measurements, technicians often experience difficulty in ascertaining the exact location of measurement points.
One method and device for assisting in the measurement of an object is the use of a mylar that may be placed upon the object to define particular locations to measure the object and/or to locate details on the object. For example, the aerospace industry typically uses large mylars with lines and points that provide reference points for measurements when the mylar is placed upon the object. Such mylars may be very large for relatively large objects, such as an airplane wing structure. These mylars can be very expensive to create and maintain, and are also time-consuming to use during the assembly or inspection of the object.
An alternative method and device for assisting in the measurement of an object includes the use of a laser projector which projects a laser beam upon the object to define particular locations to measure the object. The laser projector typically projects a single laser beam that is reflected at a very fast rate off a moving reflector such that the single laser beam appears to create a two dimensional image. Not only are such laser projectors very expensive, but they are of limited use. Images projected onto an object by a laser projector typically can not be used with a photogrammetry system as targeting on an object because during the single moment that a photo or other recorded image is captured, the image projected onto the object is not entirely visible due to the nature of the constantly moving laser beam. Furthermore, such laser projectors can not project multiple colors or large amounts of text onto the object, both of which can assist a technician during the assembly or inspection of an object.
Therefore, a need exists for an optical projection system that provides an image on an object to facilitate inspection of that object. In particular, the optical projection system should provide an image that is capable of being conveniently utilized by technicians during manual assembly or inspection of the object, or be used in connection with a photogrammetric measuring device.